Great Bugs of Fire

Great bugs of fire

Protein from volcano-loving bug crystallized in space

16 September, 1998: They may be
small, but they're very hot. They're the archaea, an ancient
branch of microbial life on Earth discovered by scientists in
1977. Unlike the better known bacteria and eukaryotes (plants
and animals), many of the archaea can thrive in extreme environments
like volcanic vents and acidic hot springs. They can live without
sunlight or organic carbon as food, and instead survive on sulfur,
hydrogen, and other materials that normal organisms can't metabolize.
It may sound like science fiction, but many scientists are working
rapidly to explore the biology as well as the practical benefits
of these recently discovered life forms.

These hot springs at Yellowstone owe their vibrant
colors to thermophilic (heat-loving) microorganisms, many of
which can live and reproduce at temperatures near the boiling
point of water. Photo courtesy Prof. Thomas D. Brock, University
of Wisconsin.

An enzyme, alcohol dehydrogenase (ADH), is derived from a member
of the archaea called Sulfolobus solfataricus. It works
under some of nature's harshest volcanic conditions: It can survive
to 88 deg. C (190 deg. F) - nearly boiling - and corrosive acid
conditions (pH=3.5) approaching the sulfuric acid found in a
car battery (pH=2). ADH catalyzes the conversion of alcohols
and has considerable potential for biotechnology applications
due to its stability under these extreme conditions. To understand
how it works, scientists first need to learn its basic structure.
For this, an Italian research team went to space.

This is one of several stories summarizing
results from the 16-day Life
and Microgravity Spacelab (LMS), which flew June 20-July
7, 1996, aboard Space Shuttle Columbia (STS-78, at launch, left).
It featured 40 scientific investigations from 10 countries. Its
record development and cost - each experiment cost about half
of most Spacelab experiments - make LMS an example of how future
space station missions can control experiments remotely from
locations around the globe. LMS results were recently published
by NASA (see below). The investigation in this story used the
European Space Agency's Advanced Protein Crystallization Facility.

Other LMS stories:

Nature's sugar
high - Spacelab successfully crystallizes
an intensely sweet protein from the African Serendipity Berry
that has 3000 times the kick of table sugar - and no calories.

Great Bugs of
Fire - Spacelab crystallizes a protein
from a very weird, and surprisingly common, volcano-loving bug.
Scientists hope to discover how these organisms can survive in
such extreme conditions. (this
story)

Nature's "electronic
ink" - Another extremophile -
a bacterium which thrives in high-salt conditions - produces
a fascinating protein which changes color extremely efficiently.
Crystals grown by Spacelab make scientists hopeful that they
can understand the biological function and apply it to, for example,
artificial retinas for people.

After collecting Sulfolobus solfataricus
from the Solfatara volcanic area near Naples, the Italian team
used the ADH enzyme for crystallization aboard the Space Shuttle.
Compared to crystals grown in Earth's gravity, the space crystals
showed an improved quality of nearly 35%, and the researchers
obtained diffraction data with a significantly higher resolution,
indicating reduced disorder. Scientists hope to use the space
grown crystals to improve the biological understanding of how
these molecules work based on a detailed knowledge of their shape
and exact atomic positions.

The red of these rocks is produced
by sulfolobus solfataricus, near Naples, Italy.

In the microgravity environment of the Space
Shuttle scientists are able to grow macromolecular crystals with
a high degree of purity. Using a process called "X-ray crystallography"
they can map the structure of proteins and learn how they work.
more information

A fundamental question posed by the space shuttle investigation
is: what features of these volcanic microbes' metabolism allows
for such thermal stability in their enzymes? If unusual characteristics
in their metabolism can be identified and studied, the transfer
of this knowledge is almost immediate to applications in environmental
cleanup, pollution prevention, or energy production. Many researchers
envision a range of medically, industrially, and environmentally
useful compounds derived from the extreme heat-loving, or "hyperthermophilic"
Archaea. Biomolecules from these organisms are active at temperatures
that generally degrade normal cellular molecules, such as enzymes,
lipids, and nucleic acids.

When stored at room temperature, these
molecules from volcanic microbes are in the "deep freeze"
compared to their normal lives, thus offering tremendously extended
shelf-life and stability in commercial use.

The first Archaea-related products were DNA polymerases for
the research market. For example, New England Biolabs, a Beverly,
Mass.-based biotechnology company, sells Vent and Deep Vent polymerases,
used in DNA sequencing. These enzymes originally were isolated
from hyperthermophiles associated with oceanic hydrothermal vents.
Without analysis of these fiery microbes, neither the modern
identification of human genetic diseases nor the use of DNA evidence
in legal courts would even have been realized.

The Archaea

Researchers say that the heat and geochemical conditions in
volcanic regions may be similar to conditions that existed on
the young, water-covered, cooling Earth. Almost like a creature
from science fiction, the volcanic microbe is different from
the two other basic branches of life: bacteria and eukaryotes.
The prokaryotes are the bacteria, while eukaryotes are the so-called
higher forms of life, including humans, plants and animals.

A major difference is that eukaryotes put their genes inside
a nucleus, while prokaryotes do not. In the archaea, there is
no nucleus, but many genes behave like those in higher organisms.
Archaea are thought to have a common ancestor with bacteria,
but billions of years ago the third domain, eukaryotes, broke
off from archaea, eventually developing into plants, animals
and us. Archaea include microbes that live at the extremes of
the planet - the very, very cold, hot or high-pressure places
that no other form of life could endure.

As such, archaea are the extremophiles who boldly thrive where
no other life form would go. Some scientists have suggested that
as such, archaea may represent the earliest form of life and
thus may be the most likely form of life existing on other planets.
About 500 species of archaea are now identified, but speculation
may not be far off in projecting that given the difficulties
of collecting and classifying them, there may be a million others.
The life form is thought to produce about 30 percent of the biomass
on Earth, much of it in the Antarctic Ocean.

In fact, as far back as 1994, Myrna Watanabe, a biotechnology
consultant, wrote that the existence of this third branch of
life "here on Earth has led scientists to realize that planets
they hitherto assumed to be lifeless might support life."

The large Jovian moon Europa may harbor liquid water beneath
its frozen crust. Many believe that large reservoirs of water
hold out the tantalizing possibility of organisms living on this
distant world. Related Story

Much work remains to be done in uncovering the shape and detailed
way that these extreme microbial molecules achieve their thermal
stability. In a controlled study comparing space grown crystals
with the best data ever previously obtained from ADH crystals
formed on Earth, the Italian team found that the "the microgravity-grown
crystals displayed increased stability when exposed to X-rays."
This finding moves the investigation closer to revealing the
biological function of these complex molecules. According to
their report, although future flights will be required to solve
the fully three-dimensional picture of the molecule, the Space
Shuttle provided larger, more ordered and more radiation-stable
examples of this microbial enzyme.

Biotechnology in space

Some estimates suggest that human biology
depends on the action of nearly half a million different enzymes
and proteins. In fewer than 1 case in 100, we have a three-dimensional
picture of shape and function of these complex chemicals. Since
1984, the Space Shuttle has carried experiments to determine
the structures of large, biologically important molecules. This
research has compiled results for a host of human diseases ranging
from insulin (for the control of diabetes) to one enzyme called
reverse transcriptase that can be blocked to inhibit HIV infection.

In comparing more than 33 such different
biological molecules crystallized on the Shuttle and also in
similar conditions on earth, space produced larger space crystals
in 45% of the cases and new structures in nearly 20% of the cases.
As many as half the space crystals had a 10% or better improvement
in the x-ray brightness or the crystallographic resolution. Both
are important to determining these large molecules' shape and
exact atomic positions.

Information

Principal investigator

Adriana Zagari, Center for the Study of Biocrystallography,
CNR and Department of Chemistry, University of Naples Federico
II, Naples, Italy